The present disclosure relates to a display device and an electronic apparatus that include a display panel having light emitting elements, for example, organic EL (Electro Luminescence) elements in each pixel, and a driving method of such a display panel.
In recent years, in the field of display devices that displays images, a display device that uses, as light emitting elements of pixels, current driving type light emitting elements, for example, organic EL elements of which luminance of emitted light changes according to values of running currents has been developed, and commercialized. Such an organic EL element is a self-luminous element different from a crystal liquid element. For this reason, a light source (backlight) is not necessary for a display device that uses organic EL elements (organic EL display device), and thus, the device can be further thinned and exhibit higher luminance in comparison to a crystal liquid display device that has a light source.
Meanwhile a current-voltage (I-V) characteristic of an organic EL element deteriorates as time elapses (time degradation) in general. When the I-V characteristic of an organic EL element changes according to time in a pixel circuit that drives a current of the organic EL element, a voltage dividing ratio between the organic EL element and a drive transistor connected to the organic EL element in series changes, and thus, a voltage between gate sources of the drive transistor also changes. As a result, since the value of a current flowing in the drive transistor changes, the value of a current flowing in the organic EL element also changes, and accordingly, luminance of emitted light also changes according to the value of the current.
In addition, there are cases in which a threshold voltage (Vth) and the degree of movement (μ) of a drive transistor change as time elapses, or Vth and μ show different values according to pixel circuits due to unevenness in a manufacturing process. When Vth and μ of a drive transistor show different values according to pixel circuits, the value of a current flowing in the drive transistor are uneven according to pixel circuits, and thus, even if the same voltage is applied to gates of the drive transistor, luminance of emitted light of an organic EL element is uneven, and accordingly, evenness (uniformity) of a screen is flawed.
Therefore, even when the I-V characteristic of an organic EL element changes as time elapses, or Vth and μ of a drive transistor change as time elapses, in order to constantly maintain luminance of emitted light of an organic EL element without being affected by such changes, a display device into which a compensating function for a variation in the I-V characteristic of an organic EL element and a correcting function for a variation in Vth and μ of a drive transistor are incorporated has been developed (for example, Japanese Unexamined Patent Application Publication No. 2008-083272).